A Walgreens spokesman said they believed the disruption was caused by an influx of people trying to schedule an appointment, crashing the server.
“We are committed to a perfect programming experience to achieve the shared goal of vaccinating our most vulnerable populations as quickly as possible,” the spokesman said.
The drop comes as U.S. pharmacies like Walgreens and CVS prepare for a million additional doses of vaccine promised by the White House last week.
To date, more than 32 million Americans have received at least one dose of a COVID-19 vaccine.
Walgreens told ABC News that as of Tuesday, they will begin accepting shooting appointments as early as Friday, prioritizing health care workers, those over 65 and people with pre-existing conditions.
ABC News contributed to this report
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